Resonant converting device, and control module and method for controlling a resonant converter

Abstract

A method for controlling operation of a resonant converter is to be implemented by a control module that generates a drive signal for controlling a power switch of the resonant converter to thereby control an output voltage and an output current provided by the resonant converter to a load. The method includes: (A) configuring the control module to determine if the load is operating in a first mode or a second mode; (B) configuring the control module to generate the drive signal according to the output voltage when the control module determines that the load is operating in the first mode; and (C) configuring the control module to generate the drive signal according to the output current when the control module determines that the load is operating in the second mode.

What is claimed is: 
     
       1. A method for controlling operation of a resonant converter, the method to be implemented by a control module that generates a drive signal for controlling a power switch of the resonant converter to thereby control an output voltage and an output current provided by the resonant converter to a load, said method comprising:
 (A) configuring the control module to determine if the load is operating in a first mode or a second mode; 
 (B) configuring the control module to generate the drive signal according to the output voltage when the control module determines that the load is operating in the first mode; and 
 (C) configuring the control module to generate the drive signal according to the output current when the control module determines that the load is operating in the second mode; 
 wherein step (A) includes: 
 configuring the control module to generate a voltage-frequency signal according to a difference between the output voltage and a predetermined reference voltage; 
 configuring the control module to generate a current-frequency signal according to a difference between the output current and a predetermined reference current; and 
 configuring the control module to determine that the load is operating in the first mode if magnitude of the voltage-frequency signal is smaller than that of the current-frequency signal, and to determine that the load is operating in the second mode if the magnitude of the voltage-frequency signal is greater than that of the current-frequency signal. 
 
     
     
       2. The method as claimed in  claim 1 , wherein, in step (B), the control module is configured to generate the drive signal corresponding to frequency of the voltage-frequency signal. 
     
     
       3. The method as claimed in  claim 1 , wherein, in step (C), the control module is configured to generate the drive signal corresponding to frequency of the current-frequency signal. 
     
     
       4. The method as claimed in  claim 1 , wherein step (C) includes:
 configuring the control module to adjust frequency of the drive signal according to the output current if the frequency of the drive signal is lower than a predetermined maximum frequency; and 
 configuring the control module to adjust duty cycle of the drive signal according to the output current if otherwise. 
 
     
     
       5. A computer program product comprising a computer-readable storage medium that comprises program instructions which, when executed, cause a control module coupled to a resonant converter to perform consecutive steps of a method for controlling operation of a resonant converter according to  claim 1 . 
     
     
       6. A method for controlling operation of a resonant converter, the method to be implemented by a control module so as to control an output voltage and an output current provided by the resonant converter to a load, said method comprising:
 (A) configuring the control module to generate a drive signal for controlling a power switch of the resonant converter to thereby control the output voltage and the output current provided by the resonant converter, the drive signal having an initial duty cycle and an initial frequency; 
 (B) configuring the control module to adjust the duty cycle of the drive signal according to the output voltage; 
 (C) if the duty cycle of the drive signal has reached a predetermined duty cycle and the output voltage has yet to reach a predetermined working voltage, configuring the control module to adjust frequency of the drive signal according to the output voltage such that the output voltage is able to reach the predetermined working voltage; 
 (D) configuring the control module to determine if the load is operating in a first mode or a second mode; 
 (E) configuring the control module to generate the drive signal according to the output voltage when the control module determines that the load is operating in the first mode; and 
 (F) configuring the control module to generate the drive signal according to the output current when the control module determines that the load is operating in the second mode; 
 wherein step (D) includes: 
 configuring the control module to generate a voltage-frequency signal according to a difference between the output voltage and a predetermined reference voltage; 
 configuring the control module to generate a current-frequency signal according to a difference between the output current and a predetermined reference current; and 
 configuring the control module to determine that the load is operating in the first mode if magnitude of the voltage-frequency signal is smaller than that of the current-frequency signal, and to determine that the load is operating in the second mode if the magnitude of the voltage-frequency signal is greater than that of the current-frequency signal. 
 
     
     
       7. The method as claimed in  claim 6 , wherein the initial frequency is a maximum allowable frequency for the drive signal. 
     
     
       8. The method as claimed in  claim 6 , wherein, in step (E), the control module is configured to generate the drive signal corresponding to frequency of the voltage-frequency signal. 
     
     
       9. The method as claimed in  claim 6 , wherein, in step (F), the control module is configured to generate the drive signal corresponding to frequency of the current-frequency signal. 
     
     
       10. The method as claimed in  claim 9 , wherein step (F) includes:
 configuring the control module to adjust the frequency of the drive signal according to the output current if the frequency of the drive signal is lower than a predetermined maximum frequency; and 
 configuring the control module to adjust the duty cycle of the drive signal according to the output current if otherwise. 
 
     
     
       11. A computer program product comprising a computer-readable storage medium that comprises program instructions which, when executed, cause a control module coupled to a resonant converter to perform consecutive steps of a method for controlling operation of a resonant converter according to  claim 6 . 
     
     
       12. A control module adapted for use with a resonant converter and operable to generate a drive signal for driving operation of a power switch of the resonant converter to thereby control an output voltage and an output current generated by the resonant converter, said control module comprising:
 a voltage subtractor for generating an error voltage from a difference between the output voltage and a reference voltage; 
 a voltage regulator for generating a voltage-frequency signal corresponding to frequency of the drive signal based on the error voltage; 
 a current subtractor for generating an error current from a difference between the output current and a reference current; 
 a current regulator for generating a current-frequency signal corresponding to the frequency of the drive signal based on the error current; 
 a comparator for comparing the voltage-frequency signal with the current-frequency signal; 
 a driving circuit for generating the drive signal; and 
 a control circuit for controlling said driving circuit to generate the drive signal according to the output voltage when it is determined by said comparator that magnitude of the voltage-frequency signal is smaller than that of the current-frequency signal, and for controlling said driving circuit to generate the drive signal according to the output current when it is determined by said comparator that the magnitude of the voltage-frequency signal is greater than that of the current-frequency signal. 
 
     
     
       13. The control module as claimed in  claim 12 , wherein, when it is determined by said comparator that the magnitude of the voltage-frequency signal is greater than that of the current-frequency signal, said control circuit controls said driving circuit to adjust frequency of the drive signal according to the output current if the frequency of the drive signal is lower than a predetermined maximum frequency, and controls said driving circuit to adjust duty cycle of the drive signal if otherwise. 
     
     
       14. The control module as claimed in  claim 12 , wherein, when it is determined by said comparator that the magnitude of the voltage-frequency signal is smaller than that of the current-frequency signal, said control circuit controls said driving circuit to generate the drive signal corresponding to frequency of the voltage-frequency signal. 
     
     
       15. The control module as claimed in  claim 12 , wherein, when it is determined by said comparator that the magnitude of the voltage-frequency signal is greater than that of the current-frequency signal, said control circuit controls said driving circuit to generate the drive signal corresponding to frequency of the current-frequency signal. 
     
     
       16. A resonant converting device comprising:
 a resonant converter for generating an output voltage and an output current and having a power switch; and 
 a control module for generating a drive signal for driving operation of said power switch of said resonant converter to thereby control the output voltage and the output current generated by said resonant converter, said control module including 
 a voltage subtractor for generating an error voltage from a difference between the output voltage and a reference voltage, 
 a voltage regulator for generating a voltage-frequency signal corresponding to frequency of the drive signal based on the error voltage, 
 a current subtractor for generating an error current from a difference between the output current and a reference current, 
 a current regulator for generating a current-frequency signal corresponding to the frequency of the drive signal based on the error current, 
 a comparator for comparing the voltage-frequency signal with the current-frequency signal, 
 a driving circuit for generating the drive signal, and 
 a control circuit for controlling said driving circuit to generate the drive signal according to the output voltage when it is determined by said comparator that magnitude of the voltage-frequency signal is smaller than that of the current-frequency signal, and for controlling said driving circuit to generate the drive signal according to the output current when it is determined by said comparator that the magnitude of the voltage-frequency signal is greater than that of the current-frequency signal. 
 
     
     
       17. The resonant converting device as claimed in  claim 16 , wherein, when it is determined by said comparator that the magnitude of the voltage-frequency signal is greater than that of the current-frequency signal, said control circuit controls said driving circuit to adjust frequency of the drive signal according to the output current if the frequency of the drive signal is lower than a predetermined maximum frequency, and controls said driving circuit to adjust duty cycle of the drive signal if otherwise. 
     
     
       18. The resonant converting device as claimed in  claim 16 , wherein, when it is determined by said comparator that the magnitude of the voltage-frequency signal is smaller than that of the current-frequency signal, said control circuit controls said driving circuit to generate the drive signal corresponding to frequency of the voltage-frequency signal. 
     
     
       19. The resonant converting device as claimed in  claim 16 , wherein, when it is determined by said comparator that the magnitude of the voltage-frequency signal is greater than that of the current-frequency signal, said control circuit controls said driving circuit to generate the drive signal corresponding to frequency of the current-frequency signal.